Intake air supplied to a combustion chamber formed in a cylinder of an internal combustion engine is cooled by a cooler before being supplied to the combustion chamber in order to improve a charging efficiency. In an internal combustion engine having a turbo charger in particular, intake air compressed by a compressor of the turbo charger is normally heated to 100 to 200° C., and therefore a heat exchanger is provided in an intake air passage on an outlet side of the compressor in order to cool the heated intake air. Heat removed from the intake air by the heat exchanger is then discharged into the atmosphere by a radiator or the like.
Patent Document 1 discloses an intake air cooling apparatus for an internal combustion engine, which includes an absorption chiller that supplies a low temperature refrigerant to a cooler that cools intake air. This apparatus will now be described using FIG. 3 (FIG. 2 of Patent Document 1). In FIG. 3, an exhaust pipe 102 and an intake pipe 104 are connected to a diesel gas engine 100. An exhaust gas passage 106 for discharging exhaust gas from the diesel gas engine 100 to the outside is connected to the exhaust pipe 102, and an intake air passage 108 for introducing outside air is connected to the intake pipe 104.
A turbo charger 110 is provided to straddle the exhaust pipe 102 and the intake pipe 104. In the turbo charger 110, an exhaust gas turbine 112 provided in the exhaust pipe 102 and a compressor 114 provided in the intake pipe 104 are formed integrally via a shaft 116. A heat exchanger 118 is interposed in the intake pipe 104. A pipeline 120 is provided between the heat exchanger 118 and an absorption chiller 122. The pipeline 120 extends into a heat exchanger 124 of an evaporator forming the absorption chiller 122. Cooling water is supplied from the absorption chiller 122 to the heat exchanger 118 through the pipeline 120.
The exhaust gas passage 106 and a heat exchanger 126 for a generator forming the absorption chiller 122 are connected by a pipeline 128. An exhaust gas heat exchanger 130 connected to the pipeline 128 is provided in the exhaust gas passage 106.
Thermal energy recovered from exhaust gas (e) flowing through the exhaust gas passage 106 by the exhaust gas heat exchanger 130 is transferred to the generator heat exchanger 126 through the pipeline 128 using steam as a medium. The absorption chiller 122 is operated by this thermal energy and cooling water transferred from a cooling tower or the like. When the absorption chiller 122 is operated, cooling water flowing through the heat exchanger 124 of the evaporator is cooled. The cooling water cooled by the heat exchanger 124 is transferred to an air cooler 118 in order to cool intake air (a) flowing through the intake pipe 104.
In this intake air cooling apparatus, the absorption chiller 122 that consumes little power is used, and heat possessed by the exhaust gas (e) is used as a heat source of the absorption chiller 122. As a result, an improvement in thermal efficiency can be achieved.
Note that FIG. 3 of Patent Document 1 discloses an example in which heat possessed by the cooling water after cooling the diesel gas engine 100 is used as the heat source of the absorption chiller.
Patent Document 1: Japanese Patent Application Publication S58-79618
Typically, a cooling tower is provided together with the absorption chiller, and the cooling water supplied to the evaporator and an absorber is cooled in the cooling tower using the latent heat of vaporization of water. For this purpose, the cooling tower requires a large amount of water. Further, when high temperature outside air is used as intake air in a region where an outside air temperature is high, such as a tropical region, the intake air compressed by the turbo charger is heated to a high temperature. Therefore, a unit that can cool high temperature intake air highly efficiently is required. Hence, when a stationary internal combustion engine is installed in a region where water is valuable or a region having a high air temperature such as a tropical region, it is difficult to obtain sufficient output.